Can Ants Harm Health?

Q: Are household ants, in large numbers, ever a health hazard? Can they contaminate food or otherwise spread germs to people or pets?

A: They could be, at least in theory, since they can carry bacteria and might transfer them to food or an open wound. Various disease-causing organisms—including E. coli, Streptococcus, Shigella, Salmonella and Staphylococcus (many of which are found in feces)—have been found on some species of ants, especially in developing countries. But there’s no evidence that this is a significant risk in the U.S.

Regardless of the health issues, no one wants lots of ants crawling on their food and furnishings. Instead of using pesticide sprays, make your home less hospitable to ants:

Store food in tight containers.

Clean up any soiled dishware and food crumbs.

Remove sources of moisture.

Follow ants to entry points, and seal cracks and crevices.

Wipe up invading ants with soapy water to erase their odor trails.

Try ant traps.

Dust boric acid (wearing a dust mask) or diatomaceous earth (silicon dioxide) into entry points, but keep these substances out of the reach of children and pets.

If you have lots of ants in your home and can’t get rid of them, you might kill a few and send them to a diagnostic lab at a United States Department of Agriculture (USDA) Cooperative Extension office, which will identify the species so that you can better target the treatment.